1. Field of the Invention
The invention relates to a rotary lock comprising a locking pin axially rotatable in a housing and comprising a shank, at each end of which a transverse latch is secured, and which pin is subject to the action of a hand lever, the rotary lock being adapted to be brought basically into three positions relatively to a corner fitting of a container for the purpose of releasably connecting two containers one upon the other. The three positions are the locking position of one first transverse latch with the other or second transverse latch in an unlocked position; the second latch in a locked position with the first latch unlocked; and with both latches in a locked position.
Rotary locks of this kind are used particularly to secure containers stacked one upon the other from slipping relatively to one another during transportation, as on a ship, in a truck or by rail. For this purpose, a container has at each corner a fitting into each of which a transverse latch can be introduced through a slot in order to be brought into a locking position to engage beneath the associated corner fitting. The second transverse latch of the rotary lock is then introduced into a corner fitting of an adjacent container disposed either above or beneath the same and locked correspondingly. Locking and unlocking are preferably effected during loading on to and unloading from the corresponding means of transport.
2. Prior Art
A rotary lock is already known from DE 36 42 399 A1, wherein to couple two containers the following three positions are traversed successively: a prelocking starting position, in which the top transverse latch is in an open position for engagement in a corner fitting of the top container, a prelocking middle position in which the bottom transverse latch is in an opened position, while the top transverse latch is pre-locked, and an end locking position in which both transverse latches are locked. For locking purposes, the rotary lock is first introduced by its top transverse latch into the slot of the bottom corner fitting of the top container, whereupon the hand lever is pivoted to produce the pre-locking middle position. The top container with the rotary lock which has the bottom transverse latch of which in the prelocked position is in the unlocked position, is then placed on the bottom container. A force storage means, which comprises at least one spring, is actuated by an actuating member which, when the two containers are driven together, is pressed into the rotary lock housing and thus prestresses the force storage means until the bottom transverse latch in its unlocked position is mounted or inserted in the corner fitting of the bottom container and then, by at least partial expansion of the force storage means, passes automatically into its locked position. A return means is also connected to the actuating member and by means of at least one other spring actuates the actuating member to effect unlocking when the hand lever is moved accordingly. Unfortunately, at least one additional spring is provided for temporarily locking the rotary locks in their locking positions. One disadvantage in particular is the very complicated construction of this embodiment of a rotary lock, which comprises a plurality of springs and in which locking of the top and bottom transverse latches takes place differently, i.e. with a different mechanism, thus accurately predetermining which transverse latch must first be brought into its locking position.
DE 37 10 419 A1 also discloses a rotary lock for releasably connecting corner fittings of adjacent containers comprising a housing and a locking pin mounted therein having at its two ends opposite transverse latches. In the basic position of the rotary lock, the top transverse latch is in its locked position and the bottom transverse latch in its unlocked position. The connection between the two containers is made as follows: firstly, the top transverse latch is rotated against the force of a tension spring until it fits in the slot of the corner fitting of the top container, and then pushed into the slot. The locking pin is then automatically brought into a prelocking position by partial expansion of the tension spring, this prelocking position corresponding to the basic position. A hand lever, which engages the locking pin, is then actuated against the force of a torsion spring to bring the rotary lock into a locking position so that the top transverse latch engages well beneath the top corner fitting and the bottom transverse latch is not in register with the slot of the corner fitting of the bottom container. When the top container is lowered on to the bottom container, the bottom transverse latch turns against the tension spring prestressing. As soon as the top container has been fully lowered on to the bottom container, the tension spring ensures that the locking position is again reached so that a transverse latch engages beneath a corner fitting. To unlock the rotary lock, the hand lever has to be unlocked manually with the torsion spring again being used. The mechanism of this rotary locking system, which requires at least two springs, is fairly complicated and requires an expensive construction in which again it is exactly predetermined which transverse latch must be locked first.
Also, U.S. Pat. No. 4,782,561, whose disclosure is incorporated by reference thereto and which claims priority from the same Japanese reference as DE 38 09 834 A1, discloses a similar rotary lock. A top transverse latch of the rotary lock is first brought into the top container corner fitting slot after unlocking by means of the hand lever, the latter then being actuated to produce a locking position in which a compression spring is operative to ensure that the top transverse latch engages beneath the corner fitting of the top container. In the next step, the top container is moved towards the bottom container so that the bottom transverse latch can be rotated into the slot of the corner fitting of the bottom container. As soon as the bottom transverse latch has completely rotated into the slot, it returns to its starting position in response to a coil spring, so that each transverse latch engages beneath the associated corner fitting. Unlocking is again obtained by reversing the movement of the hand lever. Again the very complicated structure and expensive mechanism requiring at least two springs are a disadvantage. Once again the locking of the two transverse latches differ from one another so that during locking care must always be taken to see which transverse lock must be locked first.